1. Field of the invention
The invention relates to a method for monitoring a transmission system which comprises a plurality of virtual, asynchronously time-shared transmission channels via which a data flow can be transmitted, which data flow is composed of data cells which are each transmitted by one of said transmission channels and which each comprise a control word group containing one or more control words and also an information word group containing one or more information words; in which method a number of variables is maintained which, on arrival of a data cell at a certain location, are each altered in accordance with a alteration algorithm and are then processed in accordance with an evaluation algorithm to produce an evaluation signal; in which method one or more of such evaluation signals are processed in accordance with a combination algorithm to produce a control signal and in which method a data cell is, or is not, transmitted, depending on the value of the control signal.
2. Prior art
A method as defined above is disclosed by the European Patent Application 90202268.0 in the name of the Applicant. A method is described therein for monitoring a transmission system containing a plurality of virtual, asynchronously time-shared transmission channels by means of a monitoring device. When a data cell appears at the monitoring device, a number of control and setting values with which the monitoring device is set are derived from the control word group of a data cell appearing at the monitoring device. In this way, it is possible, by means of the control word group, to make a choice from a number of variable values and, furthermore, from various parameters and algorithms with which said variable values are altered and with which the altered variable values are then evaluated. The evaluation algorithms are essentially criteria for evaluating a variable value so as to decide between alternatives, the alternatives actually being a choice between other variable values or a set of variable values, while the alternation algorithms are criteria for changing the variable values. It is also possible to deduce from the control word group the way in which the diverse evaluation results have to be combined to produce a control signal (or a plurality of control signals) which ultimately controls the access of the data cell to the downstream transmission system, in particular by means of a switching unit which, depending on the value of the control signal generated, transits, or does not transmit, the data cell concerned to the (further) transmission system.